Conventional imaging devices can generally use CCD cameras or fiber bundles to transmit images from inside the body to outside the body in the field of endoscopy. Alternatively, light beams can be scanned within the body using scanners within the devices or mechanisms such as drive shafts that convey motion from outside the body at the proximal end of the probe to the distal end that resides within the body. These techniques for conveying image information can be cumbersome, relatively large, and expensive. It can be preferable, instead, to provide a mechanically passive device that is capable of transmitting images or scanning beams inside the body.
One exemplary conventional technique for addressing this challenge can involve a measurement of transfer functions of multi-mode optical fibers or waveguides and then shaping, via changes in amplitude and phases the electromagnetic radiation prior to irradiation of a multi-mode optical fiber, so that the desired pattern is obtained at the fiber output (See, e.g., Refs 1-9). These techniques generally require that the shape, bend, twist, and stretch of the optical fiber be known a priori. However, if the fiber is bent or twisted as per usual for endoscopic procedures that occur in the body, then the transfer function is no longer known. As a result, when such techniques are utilized, the input to the fiber may not be determined, and the desired pattern may not be obtained at the output of the fiber. Alternatively for imaging applications, the destruction of the original transfer function causes the image returned from the sample to be irreparably scrambled.
This problem can be overcome by using one or more devices that allows one to gain knowledge of the fiber's bending, stretch, and twisting geometry. Methods in the art including the use of fiber Bragg gratings and Raman scattering. have been used to estimate the degree of bending and twisting of an optical fiber (See, e.g., Refs. 10 and 11).
Once the shape and twisting profile of the fiber is determined, it is possible to calculate the transfer function of the fiber.
Accordingly, there may be a need to address at least some of the above-described deficiencies or issues of these and other conventional systems and methods.